FALLING CATS
Overview
Simple physics concepts readily explain an apparent paradox: cats falling from >7 stories
show fewer injuries than those falling shorter distances. An example that engages
students’ interest, and that might be especially relevant to pre-veterinary students.
Complementary resources:
lecture/ppt slides
3 (with referenced images)
clicker questions
2 (see separate document)
homework/exam questions
Several (see separate
document)
Physics concepts
Introduces velocity, acceleration, drag, terminal velocity; gravity and mass.
 Drag as a force opposite direction of motion, and what it depends on
 Terminal velocity
o gravitational and drag forces balanced
o a=0
 Force and momentum
o what happens when you hit the ground
A good place to start looking at plots with axes of v, t, distance, and shapes of curves
Could also do free-body diagrams, connecting motion with force (im)balance.
Biological background
The explanation is really a combination of physics (terminal velocity as a function of
mass) and biological adaptation: cats, as tree-climbers, have evolved behavioral
responses to falling that minimize injury (righting response, flexed limbs, adoption of
spread-eagle posture once at terminal velocity).
© J. A. Bolker and D. C. Meredith, UNH, 2009
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Falling Cats Notes
References
Primary:
Diamond, J. 1989. How cats survive falls from New York skyscrapers. Natural
History 98:20-26.
Level: popular/general audience; easily accessible to students
Notes: The author’s main point is that “science can progress even without
controlled experiments.” Nobody threw cats out of windows: the discussion rests on an
epidemiological analysis of the injuries and outcomes of cats who ended up in veterinary
offices after falling from a known height (original data in Whitney and Mehlhaff, 1987).
Article combines physics and biology – both are described in non-technical terms, with
lots of examples/illustrations.
Additional:
Whitney, W.O. and Mehlhaff, 1987. High-rise syndrome in cats. Journal of the
American Veterinary Association 191:1399-1403. (also erratum in same journal vol.
192:542)
Level: secondary literature/review of case reports; probably not useful to students,
but source of the data discussed by Diamond, 1989.
Notes: Most of the article is summary and description of veterinary issues (types
of injuries, treatment, outcomes, etc.). The most useful part of the article in a physics
context is the final two paragraphs, which summarize data from cats and humans, and
discuss possible explanations in physical and biological terms. The brief bibliography
cites references to primary sources about falling cats and falling humans.
Kaswell, A.S. 2001. The descent of animals. Annals of Improbable Research
7(5):9-10
An annotated list of citations to nine (real) published studies about falling in cats,
dogs, rats, rabbits, and humans (including bungee jumping and falling from deer stands).
Level: popular/general audience; easily accessible to students
Notes: The annotated bibliography is a useful resource for instructors who might
want to seek detailed, primary information about descent in one or more animal species,
either for inclusion in a lecture or as grist for exam or homework questions. Alternatively
(or in addition), students could be asked to track down and use information from one or
more of the listed sources.
© J. A. Bolker and D. C. Meredith, UNH, 2009
2/2